For all that traditional evolutionary ethics is known as social Darwinism, its greatest debt is to Darwin's fellow English evolutionist Herbert Spencer. It is true that, in the Descent of Man, Darwin makes moral judgements and prescriptions – of an entirely conventional upper-middle-class Victorian ilk. It is true also that Darwin's great authority as a scientist was important. Even those who had never read the Origin often used Darwin and his standing to bolster conclusions. But it was Spencer who really counted, and thus it is to him that we turn first.

Herbert Spencer

Prima facie, at the substantive level, the social Darwinian strategy is simple and direct. One ferrets out the nature of the evolutionary process – the mechanism or cause of evolution – and then one transfers it to the human realm, arguing that that which holds as a matter of fact among organisms holds as a matter of obligation among humans (Ruse 1986a). Herbert Spencer would seem to epitomize this strategy. He started with the struggle for existence and the consequent selective effects: a connection which he made in print in 1852, years after Darwin had made the connection but years before Darwin published. He then transferred this to the human realm: not much to do here, actually, since Spencer speculated on selective effects showing themselves in the different natures and behaviours of the Irish and the Scots. He concluded that struggle and selection in society translates into extreme laissez faire in socioeconomics.